z80a: invert the meaning of IFZ, IFNZ, IFC, IFNC,

It is much less confusing when "IFZ," means "If Z is set, continue
into IF, else, jump to THEN,".

forth/boot.fs

@@ -201,7 +201,7 @@ L4 FSET L3 FSET ( loopend )
     ( HL is prev field's addr. Is offset zero? )
     A D LDrr,
     E ORr,
-    IFZ, ( noprev )
+    IFNZ, ( noprev )
         ( get absolute addr from offset )
         ( carry cleared from "or e" )
         DE SBCHLss,

forth/z80a.fs

@@ -372,10 +372,10 @@
 : BWR @ AGAIN, ;
 ( same as BSET, but we need to write a placeholder )
 : FJR, PC 0 A, ;
-: IFZ, JRZ, FJR, ;
-: IFNZ, JRNZ, FJR, ;
-: IFC, JRC, FJR, ;
-: IFNC, JRNC, FJR, ;
+: IFZ, JRNZ, FJR, ;
+: IFNZ, JRZ, FJR, ;
+: IFC, JRNC, FJR, ;
+: IFNC, JRC, FJR, ;
 : THEN,
     DUP PC          ( l l pc )
     -^ 1 -          ( l off )

forth/z80c.fs

@@ -149,10 +149,10 @@ CODE NOT
     A L LDrr,
     H ORr,
     HL 0 LDddnn,
-    IFNZ, ( skip )
+    IFZ,
         ( false, make 1 )
         HL INCss,
-    THEN, ( skip )
+    THEN,
     HL PUSHqq,
 ;CODE
 
@@ -209,10 +209,10 @@ CODE /MOD
         RLA,
         HL ADCHLss,
         DE SBCHLss,
-        IFNC, ( skip )
+        IFC,
             DE ADDHLss,
             C DECr,
-        THEN, ( skip )
+        THEN,
     DJNZ, AGAIN, ( loop )
     B A LDrr,
     HL PUSHqq,
@@ -340,10 +340,10 @@ CODE CMP
     chkPS,
     DE SUBHLss,
     BC 0 LDddnn,
-    IFZ,
+    IFNZ,
         ( not equal )
         BC INCss,
-        IFC,
+        IFNC,
             ( < )
             BC DECss,
             BC DECss,
@@ -359,13 +359,14 @@ CODE _find
     chkPS,
     ( 3 == find )
     3 CALLnn,
-    IFZ, ( found )
+    IFNZ,
         ( not found )
         HL PUSHqq,
         DE 0 LDddnn,
         DE PUSHqq,
         JPNEXT,
-    THEN, ( found )
+    THEN,
+    ( found )
     DE PUSHqq,
     DE 1 LDddnn,
     DE PUSHqq,